A variety of apparatus for carrying out this cleaning technique have been devised in the past. The simpler systems utilize a hand-held wand with one spray nozzle and one vacuum nozzle, as disclosed in U.S. Pat. No. 4,991,254, granted to James R. and Michael J. Roden on Feb. 12, 1991 for "CLEANING SYSTEM". More complex systems may employ a motor-driven rotating head with multiple spray nozzles and multiple vacuum nozzles. An example of the latter apparatus is described in U.S. Pat. No. 4,339,840 granted Jul. 20, 1982, to Clifford L. Monson for "ROTARY FLOORING SURFACE TREATING DEVICE". That same inventor was granted U.S. Pat. No. 4,441,229 on Apr. 10, 1984 for similar apparatus entitled "ROTARY CLEANER-POLISHER". U.S. Pat. No. 3,624,668 granted Nov. 30, 1971 to H. W. Krause for "RUG CLEANING AND RINSING DEVICE" discloses a similar appliance.
One undesirable operating characteristic of rotary single head cleaning devices is their tendency to veer off in different directions, depending upon the handling forces that are applied. Control of the heavy, commercial device of, say, 70-80 pounds, can be difficult and tiring for the operator.
Further, the vacuum nozzles in these devices have a tendency to chatter along the surface being cleaned and can be quite noisy in operation.
The handling characteristics of this type apparatus can be improved by employing two, counter-rotating head structures. As an example of this apparatus see U.S. Pat. No. 5,463,791 granted Nov. 7, 1995 to Michael J. Roden for "SURFACE CLEANING APPLIANCE".
There continues to be a need for a smooth running, quiet and effective cleaning appliance.